Traditional cable television systems provide one-way transmission of video information from an originating network node (usually referred to as a "head end") to a subscriber premises via a network of coaxial cables, or a mixture of optical fiber cables and coaxial cables. In the later case, the optical fiber cables each carry the video information from the head end to at least one separate network node (often referred to as a fiber node) that serves a set of subscribers in a selected geographic region. At each fiber node, the video information is converted from an optical format into one or more electrical signals that are split for distribution via coaxial cables to individual subscriber premises.
In addition to conventional one-way networks, there now exist two-way or shared networks. In a shared network, video information is delivered to the individual subscriber premises in the manner described above. The same transmission system that carries video information to each subscriber premises also carries information, typically in the form of voice, video, data, etc. from each subscriber premises back to the head end. At the head end, the information generated at each subscriber premises may be transmitted via a Local Exchange Carrier (LEC), an Other Common Carrier (OCC) or an Inter-Exchange Carrier (IXC), or any combination thereof, to another subscriber premises served by a different shared network.
In practice, the information originating at each subscriber premises within such a shared network is combined with information originating at one or more other subscriber premises prior to reaching the head end. Different types of multiplexing techniques are employed to avoid any interference or commingling of the information. When the information is combined, the noise that may be present is also combined. Even though the actual amount of noise embodied within the information that originates at one subscriber premises may be small, the total amount of the combined noise may be significant. If the noise exceeds a certain threshold, the content of the information may be lost.
Another problem that is associated with both one-way and shared networks is electrical interference that may enter the network from the subscriber premises as a result of a malfunction of the subscriber's hardware. In some instances, the inference may result from a deliberate attempt by a subscriber to jam the network. In either event, such interference may often disrupt the signals transmitted and received by other subscribers.
Thus, there is a need for a technique that reduces the incidence of overload present in a shared network because of noise and/or interference.